SMN1 and proximal spinal muscular atrophy: With SMN being expressed at high levels during embryonic and prenatal stages of development and symptoms appearing soon after birth, determining the best therapeutic time-window has become a crucial topic in the field.9 Results from individual preclinical studies in mouse models of SMA suggest that early treatment is required for maximum therapeutic benefits.10 Importantly, emerging data from recent clinical trials suggest that current therapies are, indeed, more efficient when administered in pre-symptomatic SMA Type I patients.11-13